1. Field of the Invention
The present invention relates to an AC adaptor, and more particularly, to an AC adapter with a rotative plug.
2. Description of the Related Art
AC adapters are used for various purposes such as the recharging of mobile phones and the converting of AC voltage into a desired AC voltage or a DC voltage.
For compactness and mobility, an AC adapter sometimes has a plug that can be stored in the case of the AC adapter by rotating the plug by 90 degrees to the case.
By reference to FIGS. 9A and 9B, a description on a conventional AC adapter will be given below. FIG. 9A is the front view of the AC adapter, and FIG. 9B is the cross sectional view of the AC adapter in FIG. 9A.
The AC adapter 1 is provided with a case 2 formed by insulating resin and a plug 3. The plug 3 consists of blades 4a and 4b that are made of conductive metal material and a holder 5 that is formed by molding resin material to hold an edge of each of blades 4a and 4b. A circuit board (not shown) that converts AC voltage into DC voltage is provided in the case 2.
A rotative axis 6 is extruded from the holder 5 of the plug 3. A bearing unit 7 that supports the rotative axis 6 is provided in the case 2. The plug 3 can rotate around the rotative axis 6 up to 90 degrees in the rotative direction shown by an arrow in FIG. 9A, between a state where the plug 3 is stored in the case 2 (shown by a dotted line in FIG. 9A) and another state where the plug 3 is extracted from the case 2 (shown by a solid line in FIG. 9A) for connection with an outlet (not shown). The holder unit 5 of the AC plug 3 has contacting units that are connected to the respective blades. On the other hand, the circuit board in the case 2 is provided with contacts made of leaf spring, for example. The contacting units elastically touch the contacts when the plug 3 is rotated. The detailed explanation will be given later.
In the AC adapter 1 described above, the blades 4a and 4b of the plug 3 are provided on opposite sides of the rotative axis 6 in a fashion where the wide faces of the blades face each other.
The AC adapter 1 that can store the plug 3 internally is used in a state where the plug 3 is raised after a 90-degree rotation or in a state where the plug 3 is further locked with an interlocking mechanism using a protrusion and a notch (not shown).
However, since the plug of a conventional AC adapter has a monolithic structure of blades and a holder, it is necessary to have enough space in the case of the AC adapter to store the plug, which is an obstacle to designing a small case, that is, a small AC adapter.
Accordingly, it is a general object of the present invention to provide a novel and useful AC adapter in which one or more of the problems described above are eliminated.
Another and more specific object of the present invention is to provide an AC adapter in which the size of the case can be reduced by reducing the distance between two blades of the plug when the plug is stored in the case.
According to an aspect of the present invention, an AC adapter includes a case, a plug that can be rotated by 90 degrees about one axis relative to said case, so that said plug can be stored in said case and drawn out of said case, and a blade distance adjusting unit, wherein said plug further comprises a pair of sub-holders, each holding a blade, said blade distance adjusting unit causes at least one of said pair of sub-holders to slidingly approach the other to reduce the distance between the blades when said plug is stored in said case, and to slidingly separate from the other to increase said distance between the blades when said plug is drawn out of said case.
Accordingly, when the plug is drawn out of the case, the two sub-holders separate from each other so that the distance between the blades increases up to the predetermined value. On the other hand, when the plug is stored in the case, the two sub-holders approach each other, or even contact, so that the distance between the blades is reduced. The AC adapter according to the present invention can use a thinner case than conventional AC adapters of which plugs are monolithically structured.
The AC adapter according to the present invention described above is characterized in that said plug has a rotative axis perpendicular to a plane in which said plug is rotated to be drawn out of said case, said case has a bearing unit that supports said rotative axis of said plug, said blade distance adjusting unit comprises a tongue unit formed on one of the sub-holders, said blade distance adjusting unit further comprises a convex stripe unit formed near said bearing unit, said convex stripe unit being substantially xe2x80x9cLxe2x80x9d-shaped, and said tongue unit is guided by said convex stripe unit when said plug is rotated around said rotative axis so that said distance between the blades is adjusted.
In this aspect, a stopper unit of an appropriate structure is provided at a certain position in the case. When the plug is drawn out of the case, one of the sub-holders is stopped by the stopper unit so that the distance between the blades is adjusted to a predetermined value.
That the AC adapter described above is further characterized in that said plug has a rotative axis perpendicular to a plane in which said plug is rotated to be drawn out of said case, said case has a bearing unit that supports said rotative axis of said plug, said blade distance adjusting unit comprises a protrusion unit formed on a side face of the sub-holders, said blade distance adjusting unit further comprises a guiding ditch unit formed near said bearing unit, said guiding ditch unit being substantially xe2x80x9cLxe2x80x9d-shaped, and said protrusion unit is guided by said guiding ditch unit when said plug is rotated around said rotative axis so that said distance between the blades is adjusted.
In this aspect, the distance between the rotative axis and the ditch unit is set at a predetermined value so that, when the plug is raised out of the case, the distance between the blades becomes a predetermined value. A stopper having an appropriate structure is provided at a certain position in the case. When the plug is raised out of the case, the stopper stops the sub-holder so that the distance between the blades is set at a predetermined value.
The AC adapter according to the present invention described above further includes a circuit board provided in said case, and is characterized in that each of the sub-holders has a stick-shaped contacting unit extruded in parallel to said rotative axis, said contacting unit being electrically connected to the blade held by the sub-holder, a pair of elastic contacts facing each other stand on said circuit board, said contacting unit separates from the contact when said plug is stored in said case and touches the contact when said plug is drawn out of said case.
Even in the long run, the elastic contacts damage the contacting units much less than inelastic contacts do and sustain good electric connection.
Other objects, features, and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.